The present invention relates to a low-cost, high-mass-productivity catalytic combustion apparatus having a construction that permits easy maintenance.
Many proposals have so far been made about the construction of a catalytic combustion apparatus having a heat exchanger portion. For example, as described in Japanese Patent Laid-Open No. 2000-146298, many conventional catalytic combustion apparatuses comprise a combustion chamber 2, a radiant heat-receiving portion (fin) 3, a passage 4 for a fluid to be heated, which supports the radiant heat-receiving portion, and catalytic bodies 5, 7.
In such a conventional catalytic combustion apparatus, the radiant heat-receiving portion 3 is arranged parallel to the flow of a combustion gas in order to improve the heat exchange efficiency, but the passage 4 which supports the radiant heat-receiving portion is vertical to the flow. With this construction, after forming the radiant heat-receiving portion 3 and the passage 4 that supports the radiant heat-receiving portion as separate parts, it is necessary to employ the step of press fitting, brazing or the like in order to install the radiant heat-receiving portion 3 in the passage 4.
Or after the extrusion modeling of the passage 4 and radiant heat-receiving portion 3 as an integral component part, the number of steps tends to increase due to the necessity of adopting the step of cutting, punching or the like in order to remove the radiant heat-receiving portion 3 near the position where the catalytic body 5 is to be installed. For this reason, there were problems of high cost and low mass productivity.
Furthermore, it is difficult to automate the steps of brazing etc. and labor costs tend to increase. For this reason, also in this respect, there were problems of high cost and low productivity.
The object of the invention is to solve the above-described problems with the conventional catalytic combustion apparatus.
One aspect of the present invention is a catalytic combustion apparatus in which, by means of a combustion chamber having a fuel supply portion and a combustion air supply portion on the upstream side thereof, and a combustion gas exhaust port on the downstream side thereof and a catalytic combustion portion with an upstream surface and a downstream surface provided in said combustion chamber, said upstream surface and said downstream surface being substantially parallel to each other, a fuel-air mixture supplied to the interior of said combustion chamber is caused to react to liberate heat, characterized in that said catalytic combustion apparatus comprises a heat exchange portion, said heat exchange portion constituting part of walls of said combustion chamber and a fin-type radiant heat-receiving portion, said fin-type radiant heat-receiving portion protruding from said heat exchange portion into said combustion chamber, and being provided in the vicinity of said catalytic combustion portion, and characterized in that at least the surface of said fin-type radiant heat-receiving portion and the surface of said heat exchange portion each face in the same direction.
Another aspect of the present invention is the catalytic combustion apparatus, characterized in that said catalytic combustion apparatus further comprises a convective heat transfer portion, said convective heat transfer portion being provided on the downstream side of said catalytic combustion portion so as to protrude from said heat exchange portion into said combustion chamber and having a surface facing substantially in the same direction as the surface of said radiant heat-receiving portion.
Still another aspect of the present invention is the catalytic combustion apparatus, characterized in that said heat exchange portion, said radiant heat-receiving portion and said convective heat transfer portion are integrally formed by extrusion modeling.
Yet still another aspect of the present invention is the catalytic combustion apparatus, characterized in that a surface on the side of the catalytic combustion portion, of a catalyst support which supports said catalytic combustion portion faces substantially in the same direction as the surface of said radiant heat-receiving portion.
Still yet another aspect of the present invention is the catalytic combustion apparatus, characterized in that also the surface of said catalytic combustion portion faces in the same direction as the surface of said radiant heat-receiving portion.
A further aspect is the catalytic combustion apparatus, characterized in that said catalytic combustion apparatus further comprises a heat medium passage through which a heat medium flows and a support of heat medium passage which supports the heat medium passage, and in that said support of heat medium passage is provided on said heat exchange portion so that the direction of flow of the heat medium in said heat medium passage is substantially parallel to the surface of said catalytic combustion portion.
A still further aspect of the present invention is the catalytic combustion apparatus, characterized in that the surface on the side of said catalytic combustion portion of said heat exchange portion is covered with a heat resistant coating of emissivity of about 1.
A yet further aspect of the present invention is the catalytic combustion apparatus, characterized in that said catalytic combustion apparatus further comprises a vaporizing portion which vaporizes a liquid fuel, and in that said radiant heat-receiving portion is disposed on the downstream side of said catalytic combustion portion.
A still yet further aspect of the present invention is the catalytic combustion apparatus, characterized in that upstream of said catalytic combustion portion is provided a tar holdback plate which covers the surface on the side of said catalytic combustion portion of said heat exchange portion, and which is formed from a material having a thermal conductivity smaller than that of a substrate of said heat exchange portion.
An additional aspect of the present invention is the catalytic combustion apparatus, characterized in that between said tar holdback plate and said heat exchange portion is provided a tar holdback plate support which comes into partial contact with both of said tar holdback plate and said heat exchange portion.
A still additional aspect of the present invention is the catalytic combustion apparatus, characterized in that at least one of the two walls among walls forming said combustion chamber, the two walls being substantially vertical to the surface of said radiant heat-receiving portion, is detachable.
A yet additional aspect of the present invention is the catalytic combustion apparatus, characterized in that at least one of said walls is formed from a metal or coated with a metal oxide film.
A still yet additional aspect of the present invention is the catalytic combustion apparatus, characterized in that there is provided a passage partition plate which is substantially parallel to the upstream surface of said catalytic combustion portion.
A supplementary aspect of the present invention is the catalytic combustion apparatus, characterized in that said passage partition plate and said wall are integrated.
A still supplementary aspect of the present invention is a method of manufacturing a casing portion of a catalytic combustion apparatus in which, by means of a combustion chamber having a fuel supply portion and a combustion air supply portion on the upstream side thereof and, a combustion gas exhaust port on the downstream side thereof and a catalytic combustion portion with an upstream surface and a downstream surface provided in said combustion chamber, said upstream surface and said downstream surface being substantially parallel to each other, a fuel-air mixture supplied to the interior of said combustion chamber is caused to react to liberate heat, characterized in that said casing portion comprises a heat exchange portion, said heat exchange portion constituting part of walls of said combustion chamber, a fin-type radiant heat-receiving portion, said fin-type radiant heat-receiving portion protruding from said heat exchange portion into said combustion chamber and being provided in the vicinity of said catalytic combustion portion, and a convective heat transfer portion, said convective heat transfer portion being provided on the downstream side of said catalytic combustion portion so as to protrude from said heat exchange portion into said combustion chamber and having a surface facing substantially in the same direction as the surface of said radiant heat-receiving portion, in that the surface of said fin-type radiant heat-receiving portion, the surface of said heat exchange portion and the surface of said convective heat transfer portion all face in the same direction, and in that said fin-type radiant heat-receiving portion, said heat exchange portion and said convective heat transfer portion are integrally formed by extrusion modeling.